How to store variables in flash memory

Posted by ravaz48897

on Dec 13 2008 09:43 AM

Expert1070 points

This is an example on how to use the flash for permanents variables:

Code:



 #include "hw_memmap.h"
#include "hw_types.h"
#include "hw_flash.h"

#include "flash.h"

#include 

//Declare a 1 kB block in the flash aligned on 1024 bytes boundary.
const unsigned char flashBlock[1024]__attribute__ ((aligned(1024))) = { 0x00, 0x00, 0x00, 0x00 };

//Define a structure where you can put all the
//variables you want to save in the flash.
//The maximum structure size is 1024 byte.
typedef struct tagPERMANENT_VAR
{
    int restartCount;
    int var1;
    int var2;
} PERMANENT_VAR;

//Create one instance of permanents variables.
PERMANENT_VAR permanentVars;

//This function writes the variables to the flash.
void writePermanentsToFlash()
{
    FlashErase((unsigned long) flashBlock);
    //The length must be a multiple of 4
    FlashProgram((unsigned long*) &permanentVars, (unsigned long) flashBlock, (sizeof(permanentVars) + 3) &~nbsp;3);
}

//This function reads the variables from the flash.
void readPermanentsFromFlash()
{
    memcpy(&permanentVars, flashBlock, sizeof(permanentVars));
}

//Main function example.
int main(void)
{
    //Read the variables from the flash first.
    readPermanentsFromFlash();

    //Store how many time the system restarted.
    permanentVars.restartCount++;

    //Write back the variables to the flash.
    writePermanentsToFlash();

    //Continue your program.
    //...
    //...

    while(1);
}

Post edited by: ravaz, at: 2008/12/17 20:42

Posted by joesny

on Jul 05 2010 11:19 AM

Intellectual260 points

Hi,

I was trying do your code under IAR compiler.

But this declaration does not work in IAR compile:

//Declare a 1 kB block in the flash aligned on 1024 bytes boundary.
const unsigned char flashBlock[1024]__attribute__ ((aligned(1024))) = { 0x00, 0x00, 0x00, 0x00 };


Do you know how could do this to work under IAR compiler?